In 1948, A. E. van Vogt's seminal novel The World of Null-A was published. Its main character Gosseyn has extra matter in his brain, allowing him to integrate his intellectual and animal thoughts and feelings better than other human beings. Thus, he represents the next step in human evolution. He has an unknown number of dormant clones scattered around the solar system, and when he is murdered, one of these clones awakens and retains all the memories of his predecessor. The Ophiuchi Hotline is also concerned with the future of humanity; genetic engineering is necessary for humanity to take its next evolutionary step into the cosmos. Furthermore, Varley's characters are reborn in their clones when they die. In both The World of Null-A and The Ophiuchi Hotline, the ability of the main character to survive death is important for plot development.

On the other hand, the novels...